杀灭菊酯对土壤过氧化氢酶活性的影响

为了探讨杀灭菊酯(Fenvalerate)对土壤过氧化氢酶作用的可能机制,采用室内模拟试验研究了杀灭菊酯对土壤过氧化氢酶活性和酶促反应特征参数的影响,并采用分子荧光光谱法研究了杀灭菊酯对离体过氧化氢酶构象的影响.结果表明,1)随着培养时间的延长,杀灭菊酯对土壤过氧化氢酶和离体过氧化氢酶活性的影响均表现为抑制→激活→恢复,与土壤过氧化氢酶相比,离体过氧化氢酶的抑制最低点发生前移;2)24h培养时间下,土壤过氧化氢酶抑制率与杀灭菊酯浓度呈显著正相关;3)24h培养时间下,随杀灭菊酯浓度的增加,酶促反应米氏常数Km逐渐增大,过氧化氢酶活性、酶促反应最大反应速率Vmax、Vmax/Km均逐渐减小,且各参数与杀灭菊酯浓度均显著相关,表明过氧化氢酶酶促反应特征参数可以表征杀灭菊酯对土壤过氧化氢酶活性的影响程度,其作用机理为混合型抑制;4)分子荧光光谱结果表明,随着杀灭菊酯浓度的增加,离体过氧化氢酶在352nm波长处的相对荧光强度不断增强,其分子构象发生了变化,分子渐趋疏松.

Effects of Fenvalerate on Soil Catalase Activity

In order to explore the mechanism of fenvalerate effect on soil catalase activity, the kinetics characters of soil catalase activity contaminated with fenvalerate were studied. Results showed that 1) with the increase of culture time, the action of soil catalase and in vitro catalase affected by fenvalerate showed an inhibition →activation →restoration process, and the nadir activity of in vitro catalase were ahead compared with soil catalase. 2) Under the culture time of 24h, the inhibition rate of catalase showed positive correlation with fenvalerate concentrations. 3) Under the culture time of 24h, catalase activity, Vmax, Vmax /Km of enzymatic reaction had significantly negative correlations with fenvalerate concentrations, while Km showed a significantly positive correlation. These characteristic parameters could be used as ecological indexes of catalase activity polluted by fenvalerate and the reaction mechanism of fenvalerate and catalase was mixed type of inhibition. 4) Influence of fenvalerate on in vitro catalase conformation was studied using molecular fluorescence spectrometry. After fenvalerate treatment the relative fluorescence intensity at 352nm of in vitro catalase was continuously enhanced, and catalase conformation was changed to loose.